Optimization of glutaminase-free L-asparaginase production using mangrove endophytic Lysinibacillus fusiformis B27 [version 2; peer review: 2 approved]

Background: The mangrove, Rhizophora mucronata, an essential source of endophytic bacteria, was investigated for its ability to produce glutaminase-free L-asparaginase. The study aimed to obtain glutaminase-free L-asparaginase-producing endophytic bacteria from the mangrove and to optimize enzyme production. Methods: The screening of L-asparaginase-producing bacteria used modified M9 medium. The potential producer was further analyzed with respect to its species using 16S rRNA gene sequencing. Taguchi experimental design was applied to optimize the enzyme production. Four factors (L-asparagine concentration, pH, temperature, and inoculum concentration) were selected at four levels. Results: The results indicated that the endophytic bacteria Lysinibacillus fusiformis B27 isolated from R. mucronata was a potential producer of glutaminase-free L-asparaginase. The experiment indicated that pH 6, temperature at 35°C, and inoculum concentration of 1.5% enabled the best production and were essential factors. L-asparagine (2%) was less critical for optimum production. Conclusions: L. fusiformis B27, isolated from Rhizophora mucronata, can be optimized for L-ASNase enzyme production using optimization factors (L-ASNase, pH, temperature, and inoculum), which can increase L-ASNase enzyme production by approximately three-fold.